Chapter 9, Section 1 Describing and Measuring Motion Thursday, February 11, 2010 Pages Thursday, February 11, 2010 Pages
Objectives Explain when an object is in motion and how motion is relative to a reference point. Calculate an object’s speed and velocity using SI units of distance. Graph motion showing changes in distance as a function of time. Explain when an object is in motion and how motion is relative to a reference point. Calculate an object’s speed and velocity using SI units of distance. Graph motion showing changes in distance as a function of time.
Vocabulary Words Motion Reference point Meter Speed Velocity Slope Motion Reference point Meter Speed Velocity Slope
How Do We Know Something Has Moved? An object is in motion when its distance from another object is changing. An object is moving or not depends on your point of view.
Reference Point A place or object used for comparison to determine if something is in motion. An object is in motion if it changes position relative to a reference point.
Describing Distance The SI system is used to measure distance. Distance is measured in meter. Meter is a little longer than a yard.
Calculating Speed If you know the distance an object travels in a certain amount of time, you know the speed of the object. Speed=Distance/Time If you know the distance an object travels in a certain amount of time, you know the speed of the object. Speed=Distance/Time
Constant Speed vs. Average Speed Constant Speed If the speed of an object does not change. The speed is the same at all times during its motion. Example: Merry-go- round. Constant Speed If the speed of an object does not change. The speed is the same at all times during its motion. Example: Merry-go- round. Average Speed Objects do not ove at constant speeds for a long period of time. The total distance is divided by the total time to find the average speed.
Velocity Speed in a given direction is called velocity. Velocity can be calculated if you know both the speed and the direction of an object’s motion. Speed in a given direction is called velocity. Velocity can be calculated if you know both the speed and the direction of an object’s motion.
Graphing Motion Time is shown on the x-axis (horizontal). Distance is shown on the y-axis (vertical) Time is shown on the x-axis (horizontal). Distance is shown on the y-axis (vertical)
Slope The steepness, or slant of a line on a graph is called its slope. It tells you how fast one variable changes in relation to the other variable (rate of change). The steeper the slope, the faster the motion. The steepness, or slant of a line on a graph is called its slope. It tells you how fast one variable changes in relation to the other variable (rate of change). The steeper the slope, the faster the motion.
Calculating Slope Slope = Rise/Run The RISE is the vertical difference between the two points. The RUN is the horizontal difference between the two points. Slope = Rise/Run The RISE is the vertical difference between the two points. The RUN is the horizontal difference between the two points.
Practice Graphing Begin the Practice Worksheet in class and finish for homework. Due next meeting (2/12). You can also practice online: _equation/slope-of-a-line.php graphing/slope.quiz Begin the Practice Worksheet in class and finish for homework. Due next meeting (2/12). You can also practice online: _equation/slope-of-a-line.php graphing/slope.quiz
Homework Graphing worksheet (2/12) Workbook 9.1 (2/12) Vocabulary quiz 9.1 (2/12) Graphing worksheet (2/12) Workbook 9.1 (2/12) Vocabulary quiz 9.1 (2/12)